I have a 1991 Ford Probe with a 3.0 V-6 engine. With harder acceleration I get a bad smell inside the car. I do not notice it with normal take off. Even though the exhaust system looks perfect, I believe it is the catalytic converter.
This is a tough one just going by the info you've given. If the "bad smell" you're referring to is a normal exhaust odor which is noticed only during hard acceleration, then chances are you have a small exhaust leak at the engine or real close by. The origination point could be from an emissions device, the exhaust manifold, engine pipe or the seal between the two. Sometimes a leak will be small enough that the sound is not very noticeable, but at high RPM the volume and pressure in the system increases and fills the engine compartment with fumes. In turn, it will work its way into the passenger compartment via openings at the firewall or right through the fresh air duct. (Hint: small exhaust leaks are often more audible from a cold engine)
Our second possibility is that obnoxious sulfur and/or rotten egg smell from the catalytic converter, and you smell it when you come to a stop after your 1/4 mile blast. Then the stinky fumes are coming out the tail pipe and catching up to you as you're slowing down.
Possible causes of an abnormal converter smell: A) Almost any Cat is going to emit a bad smell when the vehicle is being driven at wide-open-throttle. (B) If that's not the case, the engine may be releasing improper emissions and the cause requires diagnosis by a qualified technician using computer diagnostics and an emissions analyzer.